Answer:
Oxygen is formed from carbon dioxide in photosynthesis, while carbon dioxide is formed from oxygen in respiration.
Step-by-step explanation:
Photosynthesis is when plants make glucose and oxygen from carbon dioxide , water and sunlight. using this method plants are able to make their own food. Cellular respiration is when plants change oxygen and glucose into water and carbon dioxide along with the release of ATP. These two processes are paralels and are both necassary.